The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Known hybrid powertrain architectures include torque-generative devices, including internal combustion engines and torque machines, which transfer torque through a transmission device to an output member. One exemplary hybrid powertrain includes a two-mode, compound-split, electromechanical transmission which utilizes an input member for receiving tractive torque from a prime mover power source, preferably an internal combustion engine, and an output member. The output member can be operatively connected to a driveline for a motor vehicle for transferring tractive torque thereto. Electric machines, operative as motors or generators, generate a torque input to the transmission, independently of a torque input from the internal combustion engine. The electric machines may transform vehicle kinetic energy, transferred through the vehicle driveline, to electrical energy that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange among the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed.
During an engine start, compression torque pulses can generated in individual engine cylinders and transmitted to a transmission torque damper and an engine block, which may result in objectionable vibrations reaching the vehicle operator, especially at resonant frequencies for the powertrain and various driveline components. The compression torque pulses can disturb engine output torque and can result in objectionable audible noise. The magnitude of the vibration can be sufficiently great enough to overwhelm feedback damping control systems.
A control scheme responsive to vibrations caused during starting of an internal combustion engine is described for an engine that is an element of a hybrid powertrain system.